The field of homogeneous transition-metal catalysis has focused on the development of chemoselective, regioselective, and enantioselective catalysts and processes. Development of selective processes has been driven largely by the under-functionalized nature of petrochemical substrates. By contrast, for the efficient hydrogenation of non-food derived biomass substrates, less selective catalysts that can hydrogenate and perhaps deoxygenate a wide variety of functional groups in as few steps as possible are preferred. Preferred compositions effective for hydrogenating non-food biomass derived substrates should be tolerant of ketone and alcohol moieties present in these substrates. They should also be tolerant of water formed during the hydrogenation. They would preferably be inexpensive, and they would perform effectively at modest temperatures and pressures. These compositions would also preferably provide homogeneous catalysts because homogeneous catalysts offer a capability of rational tuning of the catalyst environment, which is not possible with heterogeneous precious metal catalysts.
Compositions derived from copper compounds and phosphines have been reported to provide homogeneous catalysts that mediate a variety of hydrogenations. They have also been reported to be tolerant to air, water, and alcohol moieties. However, the development of copper-phosphine catalysts has thus far focused on high chemoselectivity and high stereoselectivity, which are not aspects of a hydrogenation of non-food biomass derived substrates.